This patches creates two new command line options as follows:
	--backup-dir-dels=DIR
	--suffix-dels=SUFFIX

The backup-dir-dels and suffix-dels options give the ability to store
backup of removed files on the receiver in different directories or with
different suffix than the backup of files that have been changed but that
are still on the source drive.  Both commands can be combined.

The default behaviour if one or both of the options are not specified
is the previous behaviour, both backups use the same directory or
suffix.

Marc St-Onge

To use this patch, run these commands for a successful build:

    patch -p1 <patches/backup-dir-dels.diff
    ./configure                                 (optional if already run)
    make

based-on: 1ddcdaf3f6808ba53aef9e19f630a18808de22ac
diff --git a/backup.c b/backup.c
--- a/backup.c
+++ b/backup.c
@@ -29,10 +29,17 @@ extern int preserve_specials;
 extern int preserve_links;
 extern int safe_symlinks;
 extern int backup_dir_len;
+extern int backup_dir_dels_len;
 extern unsigned int backup_dir_remainder;
+extern unsigned int backup_dir_dels_remainder;
 extern char backup_dir_buf[MAXPATHLEN];
+extern char backup_dir_dels_buf[MAXPATHLEN];
 extern char *backup_suffix;
+extern char *backup_suffix_dels;
 extern char *backup_dir;
+extern char *backup_dir_dels;
+
+static int deleting;
 
 /* make a complete pathname for backup file */
 char *get_backup_name(const char *fname)
@@ -51,11 +58,28 @@ char *get_backup_name(const char *fname)
 	return NULL;
 }
 
+static char *get_delete_name(const char *fname)
+{
+	if (backup_dir_dels) {
+		if (stringjoin(backup_dir_dels_buf + backup_dir_dels_len, backup_dir_dels_remainder,
+			       fname, backup_suffix_dels, NULL) < backup_dir_dels_remainder)
+			return backup_dir_dels_buf;
+	} else {
+		if (stringjoin(backup_dir_dels_buf, MAXPATHLEN,
+			       fname, backup_suffix_dels, NULL) < MAXPATHLEN)
+			return backup_dir_dels_buf;
+	}
+
+	rprintf(FERROR, "delete filename too long\n");
+	return NULL;
+}
+
 /* simple backup creates a backup with a suffix in the same directory */
 static int make_simple_backup(const char *fname)
 {
 	int rename_errno;
-	const char *fnamebak = get_backup_name(fname);
+	const char *fnamebak = deleting ? get_delete_name(fname)
+					: get_backup_name(fname);
 
 	if (!fnamebak)
 		return 0;
@@ -96,7 +120,7 @@ int make_bak_dir(const char *fullpath)
 {
 	char fbuf[MAXPATHLEN], *rel, *end, *p;
 	struct file_struct *file;
-	int len = backup_dir_len;
+	int len = deleting ? backup_dir_dels_len : backup_dir_len;
 	stat_x sx;
 
 	while (*fullpath == '.' && fullpath[1] == '/') {
@@ -227,7 +251,8 @@ static int keep_backup(const char *fname)
 	if (!(file = make_file(fname, NULL, NULL, 0, NO_FILTERS)))
 		return 1; /* the file could have disappeared */
 
-	if (!(buf = get_backup_name(fname))) {
+	buf = deleting ? get_delete_name(fname) : get_backup_name(fname);
+	if (!buf) {
 		unmake_file(file);
 #ifdef SUPPORT_ACLS
 		uncache_tmp_acls();
@@ -380,7 +405,17 @@ static int keep_backup(const char *fname)
 /* main backup switch routine */
 int make_backup(const char *fname)
 {
-	if (backup_dir)
+	if (deleting ? backup_dir_dels : backup_dir)
 		return keep_backup(fname);
 	return make_simple_backup(fname);
 }
+
+/* backup switch routine called only when backing-up removed file */
+int safe_delete(char *fname)
+{
+	int ret;
+	deleting = 1;
+	ret = make_backup(fname);
+	deleting = 0;
+	return ret;
+}
diff --git a/generator.c b/generator.c
--- a/generator.c
+++ b/generator.c
@@ -94,6 +94,9 @@ extern uid_t our_uid;
 extern char *backup_dir;
 extern char *backup_suffix;
 extern int backup_suffix_len;
+extern char *backup_dir_dels;
+extern char *backup_suffix_dels;
+extern int backup_suffix_dels_len;
 extern struct file_list *cur_flist, *first_flist, *dir_flist;
 extern struct filter_list_struct daemon_filter_list;
 
@@ -140,10 +143,15 @@ static void handle_skipped_hlink(struct file_struct *file, int itemizing,
 				 enum logcode code, int f_out);
 #endif
 
+
+/* Function now compares both backup_suffix and backup_suffix_dels. */
 static int is_backup_file(char *fn)
 {
 	int k = strlen(fn) - backup_suffix_len;
-	return k > 0 && strcmp(fn+k, backup_suffix) == 0;
+	if (k > 0 && strcmp(fn+k, backup_suffix) == 0)
+		return 1;
+	k += backup_suffix_len - backup_suffix_dels_len;
+	return k > 0 && strcmp(fn+k, backup_suffix_dels) == 0;
 }
 
 /* Delete a file or directory.  If DEL_RECURSE is set in the flags, this will
@@ -184,9 +192,9 @@ static enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
 	if (S_ISDIR(mode)) {
 		what = "rmdir";
 		ok = do_rmdir(fbuf) == 0;
-	} else if (make_backups > 0 && (backup_dir || !is_backup_file(fbuf))) {
+	} else if (make_backups > 0 && (backup_dir_dels || !is_backup_file(fbuf))) {
 		what = "make_backup";
-		ok = make_backup(fbuf);
+		ok = safe_delete(fbuf);
 	} else {
 		what = "unlink";
 		ok = robust_unlink(fbuf) == 0;
diff --git a/options.c b/options.c
--- a/options.c
+++ b/options.c
@@ -148,10 +148,14 @@ int no_detach
 int write_batch = 0;
 int read_batch = 0;
 int backup_dir_len = 0;
+int backup_dir_dels_len = 0;
 int backup_suffix_len;
+int backup_suffix_dels_len;
 unsigned int backup_dir_remainder;
+unsigned int backup_dir_dels_remainder;
 
 char *backup_suffix = NULL;
+char *backup_suffix_dels = NULL;
 char *tmpdir = NULL;
 char *partial_dir = NULL;
 char *basis_dir[MAX_BASIS_DIRS+1];
@@ -163,7 +167,9 @@ char *stdout_format = NULL;
 char *password_file = NULL;
 char *rsync_path = RSYNC_PATH;
 char *backup_dir = NULL;
+char *backup_dir_dels = NULL;
 char backup_dir_buf[MAXPATHLEN];
+char backup_dir_dels_buf[MAXPATHLEN];
 char *sockopts = NULL;
 int rsync_port = 0;
 int compare_dest = 0;
@@ -324,6 +330,8 @@ void usage(enum logcode F)
   rprintf(F," -b, --backup                make backups (see --suffix & --backup-dir)\n");
   rprintf(F,"     --backup-dir=DIR        make backups into hierarchy based in DIR\n");
   rprintf(F,"     --suffix=SUFFIX         set backup suffix (default %s w/o --backup-dir)\n",BACKUP_SUFFIX);
+  rprintf(F,"     --backup-dir-dels=DIR   backup removed files into hierarchy based in DIR\n");
+  rprintf(F,"     --suffix-dels=SUFFIX    set removed-files suffix (def. --suffix w/o b-d-d)\n");
   rprintf(F," -u, --update                skip files that are newer on the receiver\n");
   rprintf(F,"     --inplace               update destination files in-place (SEE MAN PAGE)\n");
   rprintf(F,"     --append                append data onto shorter files\n");
@@ -608,7 +616,9 @@ static struct poptOption long_options[] = {
   {"backup",          'b', POPT_ARG_VAL,    &make_backups, 1, 0, 0 },
   {"no-backup",        0,  POPT_ARG_VAL,    &make_backups, 0, 0, 0 },
   {"backup-dir",       0,  POPT_ARG_STRING, &backup_dir, 0, 0, 0 },
+  {"backup-dir-dels",  0,  POPT_ARG_STRING, &backup_dir_dels, 0, 0, 0 },
   {"suffix",           0,  POPT_ARG_STRING, &backup_suffix, 0, 0, 0 },
+  {"suffix-dels",      0,  POPT_ARG_STRING, &backup_suffix_dels, 0, 0, 0 },
   {"list-only",        0,  POPT_ARG_VAL,    &list_only, 2, 0, 0 },
   {"read-batch",       0,  POPT_ARG_STRING, &batch_name, OPT_READ_BATCH, 0, 0 },
   {"write-batch",      0,  POPT_ARG_STRING, &batch_name, OPT_WRITE_BATCH, 0, 0 },
@@ -1458,6 +1468,8 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 			tmpdir = sanitize_path(NULL, tmpdir, NULL, 0, SP_DEFAULT);
 		if (backup_dir)
 			backup_dir = sanitize_path(NULL, backup_dir, NULL, 0, SP_DEFAULT);
+		if (backup_dir_dels)
+			backup_dir_dels = sanitize_path(NULL, backup_dir_dels, NULL, 0, SP_DEFAULT);
 	}
 	if (daemon_filter_list.head && !am_sender) {
 		struct filter_list_struct *elp = &daemon_filter_list;
@@ -1479,6 +1491,14 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 			if (check_filter(elp, FLOG, dir, 1) < 0)
 				goto options_rejected;
 		}
+		/* Clean backup_dir_dels same as for backup_dir */
+		if (backup_dir_dels) {
+			if (!*backup_dir_dels)
+				goto options_rejected;
+			clean_fname(backup_dir_dels, 1);
+			if (check_filter(elp, FLOG, backup_dir_dels, 1) < 0)
+				goto options_rejected;
+		}
 	}
 
 	if (!backup_suffix)
@@ -1490,6 +1510,20 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 			backup_suffix);
 		return 0;
 	}
+	/* --suffix-dels defaults to --suffix, or empty for a client given an
+	 * explicit --backup-dir-dels (just as --suffix defaults to empty when
+	 * a --backup-dir is given).  The second case does not apply to the
+	 * server for consistency with server_options, which sends --suffix-dels
+	 * to the server iff it differs from --suffix. */
+	if (!backup_suffix_dels)
+		backup_suffix_dels = backup_dir_dels && !am_server ? "" : backup_suffix;
+	backup_suffix_dels_len = strlen(backup_suffix_dels);
+	if (strchr(backup_suffix_dels, '/') != NULL) {
+		snprintf(err_buf, sizeof err_buf,
+			"--suffix-dels cannot contain slashes: %s\n",
+			backup_suffix_dels);
+		return 0;
+	}
 	if (backup_dir) {
 		size_t len = strlcpy(backup_dir_buf, backup_dir, sizeof backup_dir_buf);
 		if (len > sizeof backup_dir_buf - 128) {
@@ -1514,6 +1548,34 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 			"P *%s", backup_suffix);
 		parse_rule(&filter_list, backup_dir_buf, 0, 0);
 	}
+	if (backup_dir_dels) {
+		backup_dir_dels_len = strlcpy(backup_dir_dels_buf, backup_dir_dels, sizeof backup_dir_dels_buf);
+		backup_dir_dels_remainder = sizeof backup_dir_dels_buf - backup_dir_dels_len;
+		if (backup_dir_dels_remainder < 32) {
+			snprintf(err_buf, sizeof err_buf,
+				"the --backup-dir-dels path is WAY too long.\n");
+			return 0;
+		}
+		if (backup_dir_dels_buf[backup_dir_dels_len - 1] != '/') {
+			backup_dir_dels_buf[backup_dir_dels_len++] = '/';
+			backup_dir_dels_buf[backup_dir_dels_len] = '\0';
+		}
+		if (verbose > 1 && !am_sender)
+			rprintf(FINFO, "backup_dir_dels is %s\n", backup_dir_dels_buf);
+	} else if (backup_dir) {
+		backup_dir_dels = backup_dir;
+		backup_dir_dels_len = backup_dir_len;
+		backup_dir_dels_remainder = backup_dir_remainder;
+		strlcpy(backup_dir_dels_buf, backup_dir_buf, sizeof backup_dir_buf);
+	} else if (!backup_suffix_dels_len && (!am_server || !am_sender)) {
+		snprintf(err_buf, sizeof err_buf,
+			"--suffix-dels cannot be a null string without --backup-dir-dels\n");
+		return 0;
+	} else if (make_backups && delete_mode && !delete_excluded && !am_server) {
+		snprintf(backup_dir_dels_buf, sizeof backup_dir_dels_buf,
+			"P *%s", backup_suffix_dels);
+		parse_rule(&filter_list, backup_dir_dels_buf, 0, 0);
+	}
 
 	if (preserve_times) {
 		preserve_times = PRESERVE_FILE_TIMES;
@@ -1928,6 +1990,10 @@ void server_options(char **args, int *argc_p)
 		args[ac++] = "--backup-dir";
 		args[ac++] = backup_dir;
 	}
+	if (backup_dir_dels && backup_dir_dels != backup_dir) {
+		args[ac++] = "--backup-dir-dels";
+		args[ac++] = backup_dir_dels;
+	}
 
 	/* Only send --suffix if it specifies a non-default value. */
 	if (strcmp(backup_suffix, backup_dir ? "" : BACKUP_SUFFIX) != 0) {
@@ -1936,7 +2002,14 @@ void server_options(char **args, int *argc_p)
 			goto oom;
 		args[ac++] = arg;
 	}
-
+	/* Only send --suffix-dels if it specifies a value different from the
+	 * --suffix value, which would normally be used for deletions too. */
+	if (strcmp(backup_suffix_dels, backup_suffix) != 0) {
+		/* We use the following syntax to avoid weirdness with '~'. */
+		if (asprintf(&arg, "--suffix-dels=%s", backup_suffix_dels) < 0)
+			goto oom;
+		args[ac++] = arg;
+	}
 	if (am_sender) {
 		if (max_delete > 0) {
 			if (asprintf(&arg, "--max-delete=%d", max_delete) < 0)
diff -up a/proto.h b/proto.h
--- a/proto.h
+++ b/proto.h
@@ -17,6 +17,7 @@ void auth_client(int fd, const char *use
 char *get_backup_name(const char *fname);
 int make_bak_dir(const char *fullpath);
 int make_backup(const char *fname);
+int safe_delete(char *fname);
 void write_stream_flags(int fd);
 void read_stream_flags(int fd);
 void check_batch_flags(void);
